.loading {
    border: 4px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top: 4px solid #3498db;
    width: 40px;
    height: 40px;
    animation: spin 2s linear infinite;
}
@keyframes spin {
    0% {
        transform: rotate(0deg);
    }

    100% {
        transform: rotate(360deg);
    }
}